Who are these employees who install new computers, keep the corporate network running and help other workers reset their passwords? Cultural stereotypes about nerds with pocket protectors aside, what do we know about the people who keep the bits flowing and the digital lights on?

For instance, the IT guy—and they're about three times more likely to be men than women—doesn't necessarily have a computer-science degree. About a third come to IT with degrees in business, social sciences or other nontechnical fields. More than 40% of computer support specialists and a third of computer systems administrators don't have a college degree at all.

For this profile, we mainly focused on two job categories as defined by the federal Bureau of Labor Statistics: network and computer systems administrator, and computer support specialist. One way to think about these two groups is that systems administrators are charged with the upkeep of a company's back-office computer systems—servers, routers and the software to keep them working—and the support specialists are the face (or, increasingly, just the voice) of IT, who make sure other employees have the technology they need.

Demand for both administrators and support staff is expected to grow over the next decade. Jobs for systems administrators, for instance, are expected to grow 28% between now and 2020, twice the expected average growth rate for all occupations, according to the Bureau of Labor Statistics. "That's an indicator that the position is still pretty relevant in the business world," says Tim Herbert, vice president for research and market intelligence at CompTIA, a technology industry trade group.

Mr. Totty is a news editor for The Journal Report in San Francisco. He can be reached at michael.totty@wsj.com.